Conductor insulator combinations or the like



Dec. 29, 1959 CARLSQN 2,919,300

CONDUCTOR INSULATOR COMBINATIONS OR THE LIKE Filed Jan. 29, 1954 RICHARDG. CARLSON INVENTOR.

a ms ATTORNEY United States Patent CONDUCTOR lNSULATOR CONIBINATIONS ORTHE LIKE Richard G. Carlson, San Gabriel, Calif., assignor to HoffmanElectronics Corporatiou, a corporation of California Application January29, 1954, Serial No. 407,125

1 Claim. (Cl. 174-153) This invention relates to improvements inelectrical terminals and conductors and more specifically to asimplified andimproved conductor-insulator combination.

In the past a number of devices have been developed for conductingelectrical currents through a barrier of conductive material, such as achassis pan, without actually permitting the electrical currents to passinto the conductive chassis pan. Some of these devices have utilized ametal-jacketed ceramic. The outer metal jacket is soldered in place in ahole in the chassis pan and the feed-thru conductor is supported alongthe axis of the outer jacket but separated therefrom by a ceramicinsulator. Such devices are subject to destruction during the solderingoperation as a result of the dilference in the heat expansioncoeflicients of the ceramic and the metal parts of the feed-thru. Otherdevices have utilized an insulator of Teflon or the like through theaxis of which a conductor is passed, the outer diameter of the plasticcylinder being accurately set at a value extremely close to the actualdiameter of the hole in the chassis through which the feed-thru is topass. The hole in the chassis must also have accurate dimensions and becountersunk. The types of feed-thru devices just described are expensiveto install.

Therefore, it is an object of this invention to provide a simple buteffective insulated conductor-insulator combination.

It is a further object of this invention to provide an insulatedfeed-thru conductor, which may be installed in apertures which are noteasily accessible.

It is a still further object of this invention to provide an insulatedfeed-thru conductor which may be installed with ease and at minimumexpense.

It is a yet further object of this invention to provide an insulatedfeed-thru conductor which, when in operating position, will provide anair-tight seal with the chassis or other means supporting it.

According to this invention there is provided a plastic insert of Teflonor other pliable plastic which is flanged at one end and which has agenerally cylindrical shape and has a hole of predetermined dimensionspassing along its, axis for its entire length. The metal portion of thefeed-thru is constructed with sections of increasing diameter from oneend of it to the other and tapered shoulders connecting the successivelylarger sections. The section of the smallest diameter, or stem, has thegreatest length and is of a diameter substantially equal to the diameterof the aperture along the axis of the insulating insert.

To install this insulated feed-thru, a hole is cut in the chassis, thediameter of that hole being substantially that of the outer diameter ofthe smaller section of the insulator and that insulator is inserted inthe hole with the flange on the outward side of the chassis. The longthin section of the conductor is inserted in the aperture along the axisof the insulator either before or after the insulator is placed inposition in the chassis, and, with the narrow portion protruding fromthe outer face of the chassis. A simple tool has been devised to pullthis nar- 2,919,300 Patented Dec. 29, 1959 row portion outward whileholding the insulator flange against the chassis pan, with the resultthat the conductor sections of successively larger diameter are pulledinto position within the Teflon or other resilient plastic, causing thatplastic to expand forming a shoulder on the remote face of the chassisand at the same time forcing the outer walls of the plastic into verytight contact with the edge of the opening in the chassis. The result isa seal which is strong mechanically and which is resistant to thepassage of air even under pressurized conditions. An annular indentationmay be provided in the section of the conductor having the largestdiameter to assure positive retention of the conductor in the plastic.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claim. The presentinvention itself, both as to its organization and manner of operation,together with further objects and advantages thereof, may best beunderstood by reference to the following description, taken inconnection with the accompanying drawings in which:

Figure 1 is an elevational view, partially sectional, of one form of theinvention before installation;

Figure 2 is an elevational view, partially sectional, which shows thefeed-thru of Figure 1 after installation;

Figure 3 is an elevational view, partially sectional, of a secondembodiment of this invention; and,

Figure 4 is an elevational view, partially in section, showing theembodiment of Figure 3 after installation.

In Figure l, insulator 10 comprises flange portion 11 and insert portion12. Aperture 13 is drilled or otherwise formed along the axis ofinsulator 10. Conductor 14 comprises stem 15 of a first diametersubstantially equal to the diameter of aperture 13, intermediate section16 of enlarged diameter, joined by a tapered portion 17 with the firstportion 15 and by a second tapered portion 18 to terminal portion 19 ofstill larger diameter. A peripheral groove 20 may be provided for easyattachment of wires or other conductors. Conductor 14 may be made frominexpensive material in a simple screw machine operation and may then beplated so that soldering to it is simplified and to increase itscorrosion resistance.

To achieve the installed position shown in Figure 2, an aperture havingthe same contour and substantially the same diameter as insert portion12 of insulator 10 is cut in a chassis or other base 21. Conductor 14may be put in an initial relationship to insulator 10 by inserting stemportion 15 in aperture 13. This initial assembly may then be inserted inentirety in aperture 22 of base 21, with flange portion 11 of insulator10 and stem portion 15 extending from the outer face of base 21. Bymaintaining flange 10 in contact with the face of chassis or base 21while at the same time pulling stem portion 15 outwardly from that face,intermediate portion 16 will be pulled into position in aperture 13 andultimately terminal portion 19 will be pulled partially into theexpanded aperture 13 in the insert portion 12 of insulator 10. When thiscondition has been reached, insert portion 12 will fit very snuglywithin aperture 22 and a pressurized seal will be obtained betweenterminal portion 19, insert portion 12 and chassis or base 20. Insulator10 must,

-of course, be of a pliable material and a commercially In Figure 3 anadditional annular groove 300 is provided in terminal portion 19 andinsert portion 12 of insulator 10 is lengthened to compensate for theincrease in length of terminal portion 19 occasioned by the inclusion ofgroove 300.

As can be seen from Figure 4, the inner wall of insert portion 12conforms to the contour of annular groove 300 when conductor 14 reachesits installed position. A greater degree of retention of conductor 14 ininsulator 10 is thus effected.

It should be noted that with little or no modification the combinationof conductor 14 and insulator 10 may serve a standoff insulatorfunction.

Thus, it may be seen that there has been provided a conductor-insulatorcombination which may serve a feedthru or standoif insulator functionand which requires no close manufacturing tolerances, providespossibilities of hermetic sealing and is adapted to be applied to blindholes in a simple operation without soldering or complex mechanicaloperations.

While particular embodiments of the present invention have been shownand described, it is apparent that various changes and modifications maybe made, and it is therefore contemplated in the appended claim to coverall such changes and modifications as fall within the true spirit andscope of this invention.

I claim:

A conductor-insulator and apertured chassis combination of thechassis-aperture feed-through type adapted for blind installation fromone side of a chassis by a pulling operation, including a cylindricalconductor unit having an elongated stern portion, an intermediate bodyportion of larger diameter than said stem portion, a terminal portion oflarger diameter than said intermediate body portion and having anannular groove, and sections tapering toward said stem portionconnecting said portions;

and a cylindrical radially-expandible plastic insulator unit having anaxial bore sized to receive said elongated stem and whose outer surfaceis defined by an insert portion whose diameter exceeds that of theterminal portion of said conductor unit, and an adjacentchassis-engaging flange portion of still greater diameter; saidelongated stem portion of the conductor unit being substantially longerthan the total axial length of said insulator unit to enable theremainder of said conductor unit to be pulled bodily into embeddedposition within said insulator unit from the flange end thereof, therebyto produce a twostage expansion of the insert portion into sealingengagement with the wall of the panel aperture as well as into expandedupset engagement with the face of the panel opposite to said flangeportion of the insulator unit; said conductor unit being inserted insaid insulator unit and said conductor-insulator combination beinginserted in the aperture of said chassis with said panel-engaging flangecontacting one side of said chassis about said aperture and said insertportion deformed by said terminal portion of said conductor unit andengaging the other side of said chassis and with said groove lyingsubstantially in the plane of said apertured chassis.

References Cited in the file of this patent UNITED STATES PATENTS2,433,911 Johnston Ian. 6, 1948 2,436,644 Halstead Feb. 24, 19482,592,130 Erb et al Apr. 8, 1952 2,678,346 Garraway May 11, 19542,774,812 Clark Dec. 18, 1956 2,806,080 Corey Sept. 10, 1957 FOREIGNPATENTS 641,917 Great Britain Aug. 23, 1950

